#9972: Add fan morphisms
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Reporter: novoselt | Owner: mhampton
Type: enhancement | Status: needs_info
Priority: major | Milestone: sage-4.6.1
Component: geometry | Keywords:
Author: Andrey Novoseltsev, Volker Braun | Upstream: N/A
Reviewer: Volker Braun, Andrey Novoseltsev | Merged:
Work_issues: |
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Comment(by vbraun):
There is clearly important information in how the lattice spanned by a
cone is mapped to a sublattice of the lattice spanned by the image cone.
But that is just the restriction of the underlying lattice morphism, and
not associated to just any cone of the domain. You never need the
geometric image/preimage of a cone for toric geometry.
I would find it confusing if the `FanMorphism` contained any other "map of
cones" than fan morphisms. Since there is no ambiguity in "image cone",
there is no question about "preimage cones" in that category. If you want
`cones_mapping_into` and `cones_mapping_onto` for implementation purposes
that is fine, but `image_cone` and `preimage_cones` are what they are and
should be called like that.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9972#comment:57>
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